This invention relates to a process for the permanent deforming of keratin fibers, more particularly human hair, and to formulations suitable for use in this process.
The permanent deforming of keratin fibers is normally carried out by mechanically deforming the fibers and fixing the deformation by suitable auxiliaries. Before and/or after their deformation, the fibers are treated with an aqueous preparation of a keratin-reducing substance (wave lotion) and, after a contact time, are rinsed with water or with an aqueous solution. In a second step, the fibers are treated with an aqueous preparation of an oxidation agent (fixing lotion). After a certain contact time, the oxidizing agent is also rinsed out and the mechanical deforming aids (curlers, rollers) are removed from the fibers.
The wave lotion is normally alkalized so that the fiber swells and, as a result, the keratin-reducing substance is able to penetrate deeply into the fiber. The keratin-reducing substance splits some of the disulfide bonds of the keratin to --SH groups so that the peptide linkage is loosened and, through the stretching of the fibers by their mechanical deformation, the keratin structure is re-oriented. Under the influence of the oxidizing agent, disulfide bonds are re-established and, in this way, the deformation which the keratin structure has undergone is fixed.
A known process of the type in question is the permanent waving of human hair. This process may be applied both to produce curls and waves in straight hair and to straighten curly hair.
Although this process--known as permanent waving--is now widely used, it still cannot be considered to be optimal in regard to several parameters.
A crucial factor in achieving the required deformation is the so-called "strength" of the wave lotion which can be influenced through the quantity and type of reducing agent used and through the alkalinity of the wave lotion. However, wave lotions which guarantee satisfactory reshaping can cause damage to the point of breakage in the case of mismanaged hair and particularly in the case of oxidatively pretreated hair. In some cases, the scalp can also be adversely affected.
In addition, the usual acidification of the fixing lotion is not sufficient in most cases to return the hair to its original pH value within the contact time. The effect of this is that permanently waved hair is very susceptible, particularly to mechanical stressing, within the first few days of the treatment.